Sampigehalli Lake in Bengaluru is receiving sewage-contaminated water during heavy rain despite its recent restoration, raising concerns about water quality, fish deaths, public health and flooding in nearby low-lying areas. Residents, conservationists and Greater Bengaluru Authority (GBA) officials are working to identify a permanent solution, but drainage problems around the lake remain unresolved.
Residents said sewage has entered the lake through drainage channels during successive spells of heavy rain. Ravindra, secretary of the Venkateshwar Nagar residents’ association, said residents had earlier complained about sewage being discharged directly into the lake at night. After protests, a pipeline was laid to carry the discharge to the other end of the lake.
“However, we continue to notice black water and waste along the lake’s edges,” Mr. Ravindra said. He added that residents could not confirm whether sewage was still being discharged directly into the lake because the premises are closed at night. The continuing inflow has caused a heavy stench and raised health concerns among people living nearby.
Residents also said the problem could be connected to sewage treatment plants at nearby apartment complexes becoming flooded during heavy rain. If the treatment plants are overwhelmed, contaminated water could enter the lake through the surrounding drainage system. The exact source of the inflow has not yet been established, but residents say the effect is visible along the lake’s edges and has coincided with fish deaths.
The lake’s catchment area has been reduced, leaving less space for rainwater to flow into it. Residents said a mud barrier was created as a temporary measure to block one of the inlets, but they are concerned that it may not withstand heavy rain. They are seeking a permanent separation between sewage networks and stormwater drains.
The issue also reflects a wider drainage problem around the lake. Residents said water from a nearby apartment complex is sometimes diverted into the lake as an emergency measure to prevent it from flowing towards surrounding low-lying areas. They said flooding nevertheless continues, while informal settlements downstream remain at risk.
According to residents, the apartment complex has a sewage treatment plant but lacks an outlet to discharge treated water. During flooding, some water was therefore diverted into the lake. Residents said civic authorities had not yet developed a permanent solution to address the arrangement.
M. Subhadra, a resident and adjunct fellow at the Ashoka Trust for Research in Ecology and the Environment, which was involved in restoring the lake, said the situation had stabilised but that work was continuing to find a permanent solution to the inflow.
GBA officials said flooding in several parts of the city had been linked to ongoing project work, disconnected stormwater drains, low-lying areas and local structural conditions. They said they were in contact with affected residents and were working towards permanent solutions. The immediate challenge for Sampigehalli Lake is to prevent sewage and stormwater from being mixed while ensuring that emergency drainage does not shift flood risks from one neighbourhood to the lake and downstream settlements.
